The present invention relates to a method and a plant for generating carbon monoxide from hydrocarbons and CO2.
Large amounts of carbon dioxide (CO2), which is regarded as climate damaging gas, are generated in power generation and other industrial processes. Great efforts are made to avoid generation of carbon dioxide. Furthermore, attempts are made to separate the generated carbon dioxide from flue gases and to store the carbon dioxide. One example is the CO2 storage or Carbon-Capture-to-Storage concept, abbreviated CCS concept, where the CO2 is separated from the flue gases, thereafter compresses and stored in appropriate geological formations. The CCS process is expensive, energy intensive, limited in the storage capacities and is—for various reasons—strongly opposed by the respective population. At least in Germany, the technical and political feasibility seems to have failed.
Another possibility is the use of carbon dioxide as starting material for other industrial processes, i.e. as starting material in the plastics industry for producing polyurethane, as it is done by the Bayer AG in the project CO2RRECT. Regarding the amounts of involved CO2 the use of CO2 as starting material is only a niche application, since the total global production of the end products of such an application is too low to convert a significant amount of the emitted carbon dioxide.
None of these concepts resulted in applications that are able to bind large amounts of carbon dioxide or that are socially acceptable in their implementation.
Synthesis gas, or abbreviated syngas, is a gas mixture containing carbon monoxide and hydrogen that may also contain carbon dioxide. For example, the syngas is generated by gasification of carbon containing fuel to a gaseous product having a certain calorific value. The synthesis gas has approximately 50% of the energy density of natural gas. The synthesis gas may be burned and thus used as a fuel source. The synthesis gas may also be used as an intermediate product in the generation of other chemical products. For examples the synthesis gas may be generated by gasification of coal or waste. In the generation of synthesis gas, carbon may be reacted with water, or a hydrocarbon may be reacted with oxygen. There are commercially available technologies for processing synthesis gas in order to generate industrial gases, fertilisers, chemicals and other chemical products. However, most known technologies (e.g. water-shift-reaction) for the generation and conversion of synthesis gas have the problem that synthesising the required amount of hydrogen causes the generation of a larger amount of surplus CO2 which is finally emitted into the atmosphere as a climate damaging gas. Another known technology for the production of synthesis gas, the partial oxidation of methane according to the equation 2 CH4+O2→2 CO+4 H2, is able to reach a maximum ratio of H2:CO of 2.0. However, the disadvantage thereof is the use of pure oxygen that is energy intensively produced.
DD 276 098 A1 describes a more complete material utilisation of natural gas in steam reforming plants. In particular, a process for generating soot from natural gas by means of arc plasma pyrolysis is described among others. Further, U.S. Pat. No. 4,040,976 A describes treatment of a carbonaceous materials especially coal, with carbon dioxide for generating a carbon monoxide gas. In said treatment, the carbon dioxide is first mixed with the carbonaceous material and thereafter is rapidly heated in a reactor together with carbon dioxide at a rate of >500° C./s, and afterwards is rapidly cooled, wherein the heating phase lasts from 0.1 to 50 ms and the entire contact time of the reactants is limited to a time range of 10 ms to 5 s. Furthermore, generating carbon dioxide in a plasma is known from U.S. Pat. No. 4,190,636 A, where a plasma is generated from carbon monoxide, into which solid carbon is introduced. The resulting products are thermally quenched and filtered so as to obtain carbon monoxide.
EP 0 219 163 A2 discloses a method for generating synthesis gas, wherein hydrocarbonaceous material is decomposed into carbon and hydrogen in a first reactor chamber, and wherein the carbon is transferred to a second reactor chamber and reacts with H2O steam in the second reactor chamber.
GB 873 213 A2 discloses a method for generating synthesis gas, wherein first hydrocarbon is decomposed to carbon by means of a catalyst, and thereafter the catalyst in contact with the carbon is exposed to CO2.
Therefore, a problem to be solved is to provide a method for converting CO2, the method being able to efficiently reduce the amount of carbon dioxide emitted by industrial processes and to enable production of chemical products in demand.